1. Field of the Invention
The present invention relates to a semiconductor switching device with a semiconductor switching element.
2. Description of the Background Art
A semiconductor switching device for use for example in power control includes a semiconductor switching element provided in a package and having a collector electrode and an emitter electrode, a main collector electrode functioning as a terminal for guiding the collector electrode to the outside, and a main emitter electrode and a second emitter electrode functioning as terminals for guiding the emitter electrode to the outside. An example of such a semiconductor switching device is disclosed in Japanese Patent Application Laid-Open No. 8-195471 (1996).
When a current is caused to flow in the semiconductor switching device of the aforementioned structure, voltage drop is generated between the main emitter terminal and the second emitter terminal as a result of presence of a floating inductance component and a floating resistive component in the package. This voltage drop and a main current flowing from the collector electrode to the emitter electrode are in corresponding relationship to each other. So, conventionally, the main current is detected based on the voltage drop.
In the conventional semiconductor switching device, the main emitter terminal and the second emitter terminal are not close to each other. So, if a current detector for detecting the main current based on the aforementioned voltage drop is electrically connected to these two terminals, a resultant closed loop of wiring passing through the current detector and the two terminals is made relatively large. As a result, the main current to be detected by the current detector is affected strongly by inductive noise generated during switching, making it difficult to detect the main current accurately. Further, means for suppressing effect by inductive noise is not devised for an interconnect line inside the semiconductor switching device. This also makes it difficult to accurately detect the main current flowing in the semiconductor switching element.